1. Field of the Invention
The present invention relates to a fluorine-containing amphoteric polymer for surface coating and a preparation method thereof, in particular, to a fluorine-containing amphoteric polymer for surface coating and a preparation method thereof in which a hydrocarbon compound with hydrophilic groups serves as a main chain and a macromonomer prepared by copolymerization of an unsaturated hydrocarbon compound and a perfluoro alkyl compound is incorporated into side chains, thereby imparting amphoteric property on the present polymer. Therefore, the present polymer allows self-emulsification and shows soil release, water-repellent and oil-repellent properties without surfactant, applicable to a variety of industrial fields such as coating, adhesive, fiber, fine chemistry, biological/biochemical industry, electric/electronic, automobile and metal industries.
2. Description of the Related Art
Surface coating agents are widely used for their uses in various industrial fields such as coating, adhesive, fiber, fine chemistry, electric/electronic, automobile and metal industries.
Among polymers for surface coating agents, the material with improved hydrophobicity has been known very useful in the senses that it can impart on various substances properties such as water-repellent, oil-repellent, soil-release, lubricating, non-adhesion and low surface tension. Such polymer material with improved hydrophobicity can be prepared using fluorine-containing monomer with perfluoroalkyl groups. The perfluoro group [CF3(CF2)n(CH2)2—] contained in the fluorine-containing monomer exhibits super-hydrophobicity with 8 dynes/cm of critical surface tension, showing the lowest surface energy among the existing compounds. The perfluoroalkyl groups are oriented toward air at the interface of air, and the surface of the coated materials shows an extremely low surface energy.
According to the conventional process to prepare materials for surface coatings, perfluoro alkyl group-containing acrylate or methacrylate and hydrocarbon-typed acrylate with ethylene oxide (EO) adduct are subject to emulsion polymerization or radical copolymerization and then emulsified in water. Although the process shows competitiveness with respect to the simplicity and performance, it is not advantageous in that it may not produce collective surface properties due to irregular polymer configuration, thus requiring an additional emulsifier depending on the use of high-cost perfluoroalkyl acrylate (hereinafter referred to as FA). The surfactant used as an additional emulsifier elevates the surface energy at coating surface, and also forms a thin layer with nano-scaled thickness on the surface of fluoro-containing polymer. In this regard, it is difficult to perform the biological/chemical transformation using functional groups at surface, and the reaction yield is decreased and the surfactant present at surface acts as a contaminant at the time of assembly and processing by use of fluorine-containing polymer, so that the additional steps become necessary.